We have synthesized a series of overlapping fragments of mouse EGF. Biological assays of these fragments suggest that the 20-31 region of EGF is most important for binding. Using a series of synthetic fragments of mouse EGF, the antigenic determinants of mouse EGF were determined. Further work on pseudoamino acid synthesis is being carried out. Preparation of monoclonal anti-EGF is also in progress. Enzymatic resynthesis of proteins is being investigated with the object of synthesizing EGF analogs by enzymatic condensation of an appropriate peptide with an EGF fragment obtained from enzymatic degration of native EGF. In collaboration with the units listed above, we are undertaking x-ray structural studies of EGF. Using computer graphics, a modeled EGF tertiary structure was derived.